Engine cooling system control apparatus

Abstract

A cooling system control apparatus includes an electronic control unit to individually control the operation of an engine water pump, a radiator fan motor and an electromagnetic valve for bypassing the cooling water passage to the radiator, on the basis of a cooling water temperature. When the cooling water temperature is below about 85° C., the water pump is stopped to raise the cooling water temperature rapidly, and when the cooling water temperature is above about 85° C., the water pump is operated and the electromagnetic valve is operated to bypass the cooling water passage to the radiator, and when the cooling water temperature is above about 90° C., the fan motor is operated and also the electromagnetic valve is operated to allow the cooling water to pass through the radiator.

We claim: 
     
       1. A cooling system control apparatus for controlling the temperature of cooling water in a water-cooled engine comprising: a radiator for cooling said engine cooling water;   a motor-driven fan for supplying air to said radiator;   an electrically controlled water pump for circulating said engine cooling water through an engine cooling system circuit including said radiator;   an electrically controlled radiator shutter positioned to open and close an air inlet of said radiator;   electrically-controlled valve means for regulating the amount of said engine cooling water flowing to said radiator;   a water temperature sensor for electrically detecting the temperature of said engine cooling water; and   an electronic control unit for receiving at least an electric signal from said water temperature sensor to control the operation of said motor-driven fan, said water pump, said radiator shutter and said valve means in accordance with the temperature of said engine cooling water, such that when the engine cooling water temperature detected by said water temperature sensor rises above a first reference temperature T 1  representing a lowest reference temperature, said water pump is operated, and when said engine cooling water temperature rises above a second reference temperature T 2  higher than said first reference temperature T 1 , said radiator shutter is operated to open the air inlet to said radiator, and at substantially said second reference temperature T 2  said valve means opens a water passage to said radiator, and when said engine cooling water temperature rises further exceeding a third reference temperature T 3  higher than said second reference temperature T 2 , said motor driven fan is operated.   
     
     
       2. An apparatus according to claim 1, further comprising an electrically-controlled shutter drive means for actuating said radiator shutter to open and close, wherein said electronic control unit is responsive to said engine cooling water temperature indicative electric signal from said water temperature sensor to control the operation of said shutter drive means, said shutter drive means comprising a diaphragm actuator and an electromagnetic valve for controlling the air pressure supplied to said diaphragm. 
     
     
       3. An apparatus according to claim 1, further comprising a vehicle speed sensor, wherein said electronic control unit is responsive to a vehicle speed signal from said vehicle speed sensor to vary at least one of said reference water temperature T 1 , T 2  and T 3  to correct said at least one reference temperature to a higher temperature level when the vehicle speed is high. 
     
     
       4. An apparatus according to claim 1, further comprising an outside air temperature sensor, wherein said electronic control unit is responsive to an outside air temperature signal from said outside air temperature sensor to vary at least one of said reference water temperatures T 1 , T 2  and T 3  to correct said at least one reference temperature to a higher temperature level when the outside temperatures is low. 
     
     
       5. An apparatus according to claim 1, wherein said valve means is controlled by said electronic control unit to continuously increase the amount of water supplied to said radiator as the engine water temperature rises. 
     
     
       6. An apparatus according to claim 5, wherein said valve means is comprised of an electromagnetic valve and an ON-OFF cycle thereof is controlled. 
     
     
       7. An apparatus according to claim 6, wherein said electromagnetic valve is of the 3-way type which connects an engine-side passage to a radiator side passage or to a radiator bypassing passage. 
     
     
       8. An apparatus according to claim 1, wherein said motor-driven fan is controlled by said electronic control unit to continuously increase the rotational speed as the engine water temperature rises. 
     
     
       9. An apparatus according to claim 1, wherein said water pump is driven by a motor. 
     
     
       10. A cooling system control apparatus for controlling the temperature of cooling water in a water-cooled engine, wherein said water-cooled engine is mounted on an automobile equipped with a heating system which utilizes the engine cooling water as a heat source, and said heating system includes an air heating core, a blower fan for supplying the hot air heated by the heater core into a vehicle compartment, a motor for driving said blower fan, and a fan switch for switching ON and OFF the current to said motor, said cooling system control apparatus comprising: a radiator for cooling said engine cooling water;   a motor-driven fan for supplying air to said radiator;   an electrically controlled water pump for circulating said engine cooling water through an engine cooling system circuit including said radiator and through said heating system including said air heating core;   an electrically controlled radiator shutter positioned to open and close an air inlet of said radiator;   electrically controlled valve means for regulating the amount of said engine cooling water flowing to said radiator;   a water temperature sensor for electrically detecting the temperature of said engine cooling water;   means for detecting the operating condition of said blower fan of said heating system; and   an electronic control unit for receiving electrical signals at least from said water temperature sensor and said blower fan operating condition detecting means to control the operation of said motor driven fan, said water pump, said radiator shutter, and said valve means in accordance with the temperature of said engine cooling water and the operating condition of said blower fan so that when said water temperature rises above a first reference temperature T 1  or said blower fan of said heating system is in the operating condition, said water pump is operated, and when said water temperature rises above a second reference temperature T 2  higher than said first reference temperature T 1 , said radiator shutter is operated to open the air inlet to said radiator, and at substantially said second reference temperature T 2  said valve means opens a water passage to said radiator, and when said water temperature rises further exceeding a third reference temperature T 3  higher than said second reference temperature T 2 , said motor driven fan is operated.